Traffic control signal



2 Sheets-Sheet l Filed Feb. l, 1935 Nov. 1, 1938.

A. P. EsgREhlsi-lxwy TRAFFIC CONTROL SIGNAL Filed Feb. l, 1955 2 Sheets-Sheet 2 A TTORN Y? yzo Patented Nov. 1, 1938 um'rlazov STATES PATENT OFFICE TRAFFIC CONTROL SIGNAL Alfred Percy Bailey Renshaw, Kingston Hill, England, assigner, by. mesne assignments, to Automatic Telephone &

Electric Company Limited, London, England 12 Claims.

The present invention relates to traic control signals for use at road junctions or the like and is more particularly concerned with systems in which thev period of display of the appropriate signals is controlled by vehicle detectors located in the various trafiic routes. In systems of this type the purpose of going to the extra expense of providing vehicle detectors is to ensure by their use that right of way shall never be retained by a road on which there is no traffic while trafficis Waiting to pass on an intersecting road. It is usually arranged that a vehicle actuating a detecto-r secures to itself right of way for a period sufficient to enable it to clear the crossing and this period may vary in accordance with the speed of the vehicle. Accordingly the length of the right of way period allowed to any one road may be repeatedly extended if vehicles` follow each other suiciently closely thereon, and in order that vehicles on an intersecting road shall not be unduly held up it is usual to provide separate timing means to set a limit to the time during which one road can hold right of way if vehicles are waiting on an intersecting road.

It is also recognized that if a number of vehicles are brought to rest while they are awaiting right rof way, an additional time will be necessary to permit them to get into motion and clear the crossing. It has been suggested that this additional time should be proportional to the number of vehicles waiting but an allowance on this basis is unduly extravagant and a compromise which is found reasonably satisfactory in practice is to allow a short xed period to coverl the delay involved in starting up from rest. This period Vhas become known as the initial interval as distinct from the vehicle interval which represents the maximum extension which can be obtained by a slow moving vehicle actuating the detector at a time when the road in question possesses right o-f Way. Thus with this arrangement a single vehicle approaching the intersection in theabsence of other traic would generate a right of way period made up of the initial interval and one vehicle interval and this would 4represent the minimum time during which right of way could be displayed.

It has been found that with suitable choice of the initial and vehicle intervals to meet local conditions this arrangement gives good results but a refinement is possible in the case in which a vehicle receives right of' way immediately it actuates the detector and therefore does not need to slow down. It will be appreciated that in this case there is no need to provide any initial interval and this time period may therefore be made available to the intersecting road if there is any traffic thereon. The chief object of the invention is to provide a simple arrangement whereby this refinement may be secured in practice and thus the advantages of the vehicle-actuated type of system are still further increased as against the xed time system.

According to one object of the invention in a. traliic signalling system arranged to give right of way to a number of intersecting trahie routes in turn under the control of vehicle detectors located in one or more of the traffic routes right of Way is normally displayed to any one lane for a predetermined minimum period but is adapted to be displayed for a shorter period under particular traffic conditions.

According to another object of the invention, in a traflic signalling system arranged to give right of way to a number of intersecting traic routes in turn under the control of vehicle detectors located in one o-r more of the traflic routes due to a vehicle actuating a detector in a traffic route not possessing right of way, right of way is secured to that route for a predetermined period while if this right of way is not given immediately a further period is secured to the traffic route to compensate for the check to the speed of the vehicle.

A further object of the invention is to provide in a traffic signalling system arranged to give right of way to a number of intersecting traflic routes in turn under the control of vehicle detectors located in one or more of the traffic routes and arranged so that the period during which right of way is displayed comprises an initial interval designed to give waiting vehicles time to get into motion and one or more vehicle intervals each representing the extension produced by an operation of the detector at a time when the traffic route in which it is located possesses right of way, that if the operation of the detector in one route results in right of way being transferred immediately to that route, the initial interval on that route is substantially reduced.

The invention will be better understood from the following description of one method of carrying it into effect, and which may advantageously be employed with a right of way controller whose operation is dependent upon actuation of traffic actuatable detectors in one or more of the several approaches to the intersection.

The description will be made clearer with reference to the accompanying drawings which illustrate one practical embodiment of the invention, and in which Figure 1 is a wiring diagram of a type of right of way controller whose operation through its cycle of signal indications is dependent upon actuation of traiic actuatable detectors in the several approaches tol the intersection.

Figure 2 shows the modifications required in accordance with the invention in a right of way controller of the type shown in Figure 1 so that it will function as outlined above.

An embodiment of right of way controller for use at intersections of interfering trafc lanes which may advantageously employ the apparatusof the present invention will now be described. Signal indications from a controller ofV this type are operated in accordance with the density of the traffic by the employment of vehicle detectors located in the roadway.

Vehicle detectors may be of the type in which two resilient conductor sheets are flexed into contact with each other by the weight of a passing vehicle, or any other type which will upon the passage of a vehicle control an operating circuit,- as by electromagnetic, photo-electric, or other means.

The controller diagrammatically represented in Figure l is provided with a number of sets of contacts operated by a camshaft which is moved through its cycle step by step by means of a solenoid. The stepping of the solenoid is controlled fromy a timing circuit which may employ ak gas discharge tube-condenser combination, the timing being variable and under the control of vehicle detectors in the roadway. Two separate timing circuits are employed and two road relays which respond to the passage of vehicles over the detectors are provided. n

The current supply is assumed to be taken from alternating current mains and. is rectied to provide direct current for the operation of the discharge tubes.v The transformer XFR. feeds the valve rectifier VR. The live pole of the A. C. circuits is represented by a plus in a circle, `the live pole of the D. C.` circuits by a plus in a square, and the common grounded pole by a minus in a circle and a quare. 'I he chart shows'the postions of the camshaft in which the various cam contacts are closed. The various contacts of the several interval adjusting switches INS, VNS, IEW, VEW, LNS, LEW, are wired toappropriate tapping points of the resistance 20, and similarly the switches MNS, and MEW are wired to resistance 2| which gives tappings of higher value. Y

For convenience of description it will be assumed rst of all that the cam shaft isstanding in position 6 giving right of way to the street NS and that there is no traflic on either street. In these circumstances a charging circuit is completed over contacts C4 and the adjusting switch VNS for the condenser QA, but owing to the fact that neither relay D nor relay E is operated in the absencey of traiiic assumed and the consequent absence of closure of road contacts DEW and DNS, and with contacts d2' therefore open, it is impossiblefor discharge to take place through the discharge tube FA when the Vcondenser becomes charged to the striking voltage. Moreover while contacts d2 remain open no chargingrcircuit is Suppose now that a Vehicle arrives on Vthe roadY EW, relay D willbe energized due to the operation of a detector DEW and since contacts C6 are closed, a circuit is completed over armature d2 for striking tube FA so that relay A is energized and the solenoid is operated at armature al and the cam shaft is moved to position l. In this position the lamp REW remains operated, lamp ANS is lighted in place of GNS, and lamp AEW is lighted in addition to lamp ANS if the switch AS is closed. Moreover, a new charging circuit is completed for condenser QA over cam contacts CIS, the adjusting switch LNS and the appropriate charging resistance. Relay D moreover was locked up over armature dl and contacts Cl' so that as soon as the condenser QA has been charged suiiiciently which will occur after a few seconds only, relay A is again operated and advances the cam shaft to position 2. In this position lamps GEW and RNS only are lighted and the vehicle in the street EW secures right of way. Furthermore a new charging circuit is now completed for condenser QA, this time over contact C|4 and switch IEW. Consequently, after the period corresponding to the resistance now included in the charging circuit, relay A is again operated and the solenoid steps the cam shaft to position 3. This produces no change in the lights but the charging circuit for condenser QA now extends over contact CIS and the switch VEW and moreover relay D is de-energized by the opening of contacts C1 while owing to the closure of contact CIG a circuit is prepared for shunting condenser QA. If there is no further traflic, right of way will remain on the EW road and the condenser QA will become fully charged.

If further Vehiclesarrive on the EW road however relay D isY again operated and shunts the condenser by way of the comparatively low resistance YE and contacts CBS and d2 and thus extends the time which will be required for the condenser to be charged to the striking Voltage ,of the discharge tube FA. It may be pointed out that since in these circumstances relay D is only operated while the vehicle is actually passing over the detector pad, the amount of extension obtained is dependent on the speed of the vehicle, being greater for a slow moving vehicle than for a fast movingv one.

If now a vehicle should arrive on the road NS, relay E will be operated and contacts Cl'l' will complete a circuit for eiecting the operation of relay A as soon as Vcondenser QA is suiliciently charged. Hence, if a break of suiicient length to permit the striking voltage of the discharge tube FA to be reached occurs in the traino on the road EW, relay A will be operated and will advance the cam shaft to positions 4, 5 and E in turn in the manner previously describedto give right of way to the road NS.

In case, however, the traffic on the road EW should be substantially continuous, that is to say, there should be no break suiciently long to permit condenser QA to charge up, the maximum timing circuit involving the condenser QB comes into operation. It will be noted that this circuit cornes into operation as soon as there is a waiting vehicle on the road NS at which time relay E is operated and locks up over contacts Cl8. The

v charging circuit for condenser QB now extends road NS as soon as the condenser QB becomes sufliciently charged to reach the critical value of discharge tube FB, whereupon the relay B is energized and through its contact b| operates solenoid S, which notches the camshaft into its nextrfposition.

It will he noted that armatures d3 and e3 when operated serve to include additional resistances YF and YG in their respective amber timing circuits so that when right of Way is being forcibly removed from a lane thus intercepting a stream of traic an extended amber period is given to facilitate clearing the crossing. 'I'his feature may be rendered ineffective by closing the amber extension switches ENS, EEW.

The switches PNS and PEW are so-called arterial' switches and when closed ensure that right of way shall return to the associated street in the absence of traffic thereon. Their effect is to simulate the operation of the pads at a time when the street in question is not receiving right of way by energizing the respective relays E- and D in cooperation with cam contacts CIS and Cl respectively, in all positions except 6 and 3 respectively,'though they do not produce any extension eiiect when the street already has right of way,

Vsuch extension being produced only by operation of thefproper road pads.

vThe solenoid S is provided with three sets of contact springs of which Sl and S2serve to shunt condensers QA Yand QB by low resistances YA and YB respectively. Springs S3 are effective in conjunction with armature h2 to ensure that without any further operation of the associated detector right of way shall be returned to the street from which it has been forcibly removed.

In Figure 2 are shown the modifications to a controller of the type illustrated in Figure 1 to obtain a substantial reduction or in practical effect the elimination of the initial interval in the case where a vehicle actuating a detector in a traiiic lane which has been denied right of Way immediately secures transfer of right of way in its favor. The additional equipment required according to one embodiment of this invention comprises the discharge tube FC, relay C, relay F, a ypair of cam contacts C3, resistance YH, and/a fourth set of springs on the solenoid S. The tube FC is chosen to have a somewhat higher striking voltage than the tube FA. The additional cam contacts C8 are closed in shaft positions l, 2, 4, and 5, as will subsequently appear.

A circuit including in series the added discharge tube FC' and relay C parallels tube FA and relay A from resistance 20 to lead 25. By its armature cl relay C is arranged to energize relay F, which has a lock-in circuit over its armature fl, and over either cam contacts C8 or over solenoid springs S4 in parallel therewith. Armatures f2 and f3, in the normal cle-energized position of relay F, complete the normal timing circuits for the initial interval on both the EW and NS roads. When relay F is energized, however, the charging circuit to timing condenser QA is closed over either of the armatures f2 and f3 across resistance YH which is low in value relative to the normal initial interval charging resistances.

Considering now the operation of the circuit, if right of Way remains with either road for appreciably more than the period of the last vehicle extension, the voltage of condenser QA will rise above the striking values ofthe discharge tubes FA and FC which do not strike however as their circuit is open at cam contacts C5 or Cl.

Suppose now a vehicle approaches on the road not possessing right of way, the corresponding road relay E or Diligure 1) will operate and accordingly both tubes FA and FC will strike and bring about the operation of their associated relays A and C. Relay A completes the circuit of the solenoid for stepping the cam shaft in the usual` way, and relay C' operates relay F which holds during the stepping over the contacts S4 which are closed during the operating period of the solenoid. When the step is completed, relay F remains locked over cam contacts C8 which are closed during the amber and initial intervals. Relay F at armatures f2 and f3 disconnects the normal initial interval timing circuits and completes a quick-step circuit by way of the low resistance YH, so that the controller immediately steps through the initial interval position into the vehicle interval' position. Under these circumstances therefore, the timing of the initial interval is eliminated and when the cam shaft comes into the vehicle interval position, the cam contacts C8 again open and relay F releases to restore the circuit to normal.

If, however, a vehicle arriving against the red signal has to wait either for a gap in the opposing traftic or for the expiration of the maximum period, the special arrangements described are not eiective, since both discharge tubes FA and FC are in circuit while the condenser QA is charging and the voltage does not rise above the striking value of tube FA to reach the striking voltage of tube FC, and accordingly relay C is not operated.

The invention is not limited to systems in which vehicle detectors are provided in all the roads forming the intersection and nds equal application in systems in which vehicle detectors are provided in the side roads only though in this case of course it can only reduce the initial interval in the right of way period for the side roads. In such systems when the minimum right of way period on the main road has expired, it is clearly undesirable that a vehicle on the side road which obtains immediate right of way should be provided with an initial as well as a vehicle interval, thereby keeping -the important main road traffic waiting unnecessarily. Under these circumstances, therefore, when the minimum period for the main road has expired and a call is made from the side road, the tube FC will strike and operate relay F so as to ensure that the initial interval on the side road shall be eliminated.

It will be appreciated that if a vehicle arrives on the side road to operate relay D while the charge on condenser QA is rising between the striking value of tube FA and the striking value of tube FC, then only tube FA and relay A will operate and the following side road initial interval will be of normal full length, just as in the case of the vehicle arriving before the condenser charge reaches the striking value of tube FA. However, the dilerence between the striking voltages of tubes FA and FC may preferably be quite small, so that the time to reach the striking value of tube FC will be only slightly longer than the time to reach that of tube FA and the longer timer interval may be considered substantially the same as the vehicle interval of right of Way timed primarily by tube FA.

Where vehicle detectors are provided in both intersecting roads, a vehicle actuating a detector on the road having right of way will extend the right of way period during the vehicle interval by discharging condenser QA and under these circumstances reduce thecondenser voltage bethe transfer of right of Way to the opposite roadV in response to a vehicle actuation then occurring there and until the charge on condenser QA reaches and operates FA, and thus will cause the subsequent initial interval in the opposite road to be of normal full length.

Thus the several objects speciiically brought out above, and others are achieved. It is to be understood that various modifications in the structural details or arrangement of the parts, or changes in the designs herein exemplied may be made without departing from the spirit of the invention as defined by the claims.

Having described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

i. A traffic control system for interfering trafiic lanes having traffic actuatable means in each of the lanes, a first set of circuits including signais for according right of Way to one of the lanes and interrupting right of Way to the other lane, a'second set of circuits including signals for according right of Way to said other lane and interrupting right of Way to said one lane, a right of Way controller connected to said traiiic actuatable means and to said signalling circuits for controlling the latter and including a cyclic switch having two parts to its cycle, and adapted in one part of its cycle to energize said first set of signalling circuits and in the other part of its cycle to energize said second set of signalling circuits, means forming a part of said controller and operable while said switch is in said other part of its cycle and when actuation of the traiiic actuatable means in said one lane occurs before or at the time of expiration of a minimum period to move said switch to said one part of its cycle for a normal predetermined minimum pericd'of time and means operable when actuation of said trafc actuatable means occurs` after expiration of said minimum period while said switch is still in said other part of its cycle to move substantially immediately said switch to said one part of its cycle and for a shorter than normal predetermined minimum period of time. Y

2. In a traffic signal control system for the intersection of trafIic lanes, a right of Way controller for according and interrupting right of Way on the said lanes, a traffic actuatable device in one of the lanes and connected to said controller tov govern operation of same, a timing apparatus forV timing a minimum right of Way period on a second lane, and having a condenser, means for charging said condenser, means operable in response to a predetermined charge on the condenser and connected to said condenser upon actuation of the said actuatable device, means operable in response to a higher predetermined charge on the Condenser and connected to said condenser upon actuation of said actuatable device, means functioning upon operation of the first mentioned charge responsive means for providing a normal minimum period of right of way on the lane of actuation, and further means functioning upon operation of the second charge responsive means for providing a shorter than normal minimum on said lane of actuation.

3. In a traic signal control system for the intersection of traiiic lanes, a right of way controller for accordingand interrupting right of Way on the lanes, a traiiic actuatable device in one of the lanes and connected to said controller to govern operation of same, said controller including means to accord right of way to a sec-,- ond laneY for at least a Ininimum period and in the absence of actuation of said device to maintain said rightof Way beyond said minimum, a timing apparatus having a condenser, means including a high resistance in series with the condenser for charging said condenser and a gas discharge tube having a certain operating voltage in parallel with said condenser, the period timed by said timing apparatus being determined by the charging of said condenser thru said high resistance to the operating voltage of said discharge tube, one such high resistance connectible in the charging means to time a normal minimum period of right of Way on the lane of the said traiiic actuatable device, a second such resistance of different value from the iirstand connectible in the charging means in place of the rst to time a shorter than normal minimum period of Yright of way onk the said lane, means operable when actuation of the traiiic actuatable device in the said one lane occurs before or at the time of expiration of a minimum right of Way period on the second lane to connect said one such high resistance in the timing circuit, and means operable upon actuation after expiration of said minimum right of way period on said second lane and while right of way is still accorded to said second lane to Vconnect said sec ond resistance in the timing circuit.

4i. In a traiiic signal control system for the intersection of interfering trafiic lanes having a right of way controller for according and interrupting right of way on the said lanes and a traic actuatable device in one of the lanes and connected to. said controller to govern operation of same, said controller including a timing'arrangement having a condenser, a resistance, means for charging said condenser through said resistance, and means operable in response to a predetermined charge on the condenser, means functioning upon operation of said charge responsive means when right of Way is on said one lane to transfer right of Way to a second lane, further means functioning upon operation of said charge responsive means when right of Way is on said second lane to transfer right of Way to the first lane, a second charge responsive means operable in response to a predetermined charge higher than the rst charge responsive means, means acting upon actuation of said tralic actuatable device When the right of way is on said second lane to connect both of said charge responsive means to said condenser, means functioning only vupon operation of said second charge responsive means to decrease the resistance in said charging means in the next period of right of Way on said first lane.

5. In a traffic signal control system for the intersection of traiiic lanes, a right of Way controller for according and interrupting right of Way on the said lanes, a traiiic actuatabledevice in one of the lanes and connected to said controller to govern operation of same, a condenserelectronic tube timing arrangement for timing a minimum right of Way period on a second lane, and having a condenser, means for charging said condenser, means when connected to said condenser operable in response to a predetermined charge on the condenser for providing a normal minimum period of right of Way on the lane of the actuatable device, means When connected to said Condenser operable in response to a higher predetermined charge on the condenser for providing a shorter than normal minimum period of right of Way on said lane of the actuatable device, and further means operable rupon actuation vof the traillc actuatable device while right of way is being denied to the lane Vof said device for connecting both of said means to said condenser.

6. In a traffic signal control system for the intersection of interfering trailic lanes, having a right of way controller, and a traiiic actuatable device in one of the lanes and connected to said controller to govern transfer of right of way by said controller between said lanes, a camshaft and contacts operating therewith for controlling right of way signal circuits and means for rotating said camshaft forming a part of said controller, a timing apparatus also forming a part of said controller to provide minimum time periods for such right of way and having a condenser, means for charging said condenser, means operable,.when connected to said condenser, inresponse to a predetermined charge on the condenser to operate said camshaft rotating means, and to cause the next minimum period o fright of way on the lane Yof actuation to be of a predetermined length, and means operable, when connected to said condenser, in respons'e 'to a higher predetermined charge onv the condenser to cause said next minimum period of right of way on the lane of actuation to bev intersection of interfering trahie. lanes, having a rightr of way controller, and a traffic actuatable device in one of the lanes and connected to said controller to govern transfer of right of way by said controller, means in said controller operating in response to actuation of said device for according right of way to the lane of the actuatable device for the duration of an initial interval plus a variable vvehicle interval and then to a second lane for at least a fixed minimum interval and thereafter in absence of actuation in the iirst lane, a timing apparatus for determining the extent of each of said intervals including a condenser and means for charging said condenser, means operable in response to a predetermined charge on said condenser for advancing said right of Way according means from one interval to the next for one lane and then another,

means operable when actuation of the traiic' actuatable device in the said one lane occurs before or at the time of expiration of said minimum interval for said second lane to control said condenser-charging means to cause said initial interval period of right of Wayon said first lane to be of normal duration, and means operable when actuation of the traffic actuatable device in the said one lane occurs after expiration of said second lane minimum interval to control said condenser-charging means to provide a shorter than normal initial interval period on said first lane.

8. In a traffic signal control system for the intersection of interfering trafiiclanes, having a right of Way controller, and a traic actuatable device in one of the lanes and connected to said controller to govern transfer of right of way by said controller, means in said controller operating in response to actuation of said device for according right of Way to the lane of the actuatable device for the duration of an initial interval plus a variable vehicle interval and then to a second lane for at least a fixed minimum interval and thereafter in absence of actuation in the first lane, a timing apparatus for determining the extent of each of said intervals and having a condenser, means including a resistance connectible to said condenser for charging said condenser, and means operable in response to a predetermined charge on said condenser for cyclically advancing said right of way according means from one interval to the next for the one lane and then another, means operable when actuation of the traflic actuatable device in the said one lane occurs before the time when the said predetermined charge on the condenser has been reached in the minimum interval on said second lane to connect said resistance in said condenser charging means for timing the next initial interval period of right of way on said iirst lane, and further means operable when actuation of the said device occurs after said predetermined charge on the condenser has been reached in the minimum interval on said second lane to substitute a substantially lower value of resistance in said charging means for said next initial interval.

9. In a traino signal control system for the intersection of a plurality of interfering traiic lanes, a right of way controller for according and interrupting right of way, traffic actuatable devices in the several lanes for governing the operation of said controller, means in said controller 'f for timing a right of way period for each one of the lanes at a time in turn said period consisting of a fixed initial interval and a vehicle interval of at least a predetermined length, means respon/- sive to actuation in a lane having right of way while said last named means is timing the vehicle interval of right of way on such lane for extending said vehicle interval right of way period beyond said predetermined length by resetting said last named means, and means responsive to actuation of the traino actuatable device in one lane occurring more than a period of said predetermined length after any actuation on a second lane and while right of way is still on said second lane to substantially reduce the next following initial interval on said one lane when said controller next accords right of way to said one lane.

10. In a traffic signal control system for an intersection of traffic lanes having a vehicle responsive device in one lane, a right of way controller to transfer right of way to said one lane from a second lane in response to actuation of said vehicle responsive device in the rst lane and thereafter to retransfer right of way to said second lane, a condenser and a charging circuit connected thereto, means including a discharge tube cooperating with said condenser to time a minimum period of right of way in said second lane before-transfer to said rst lane in response to actuation of said device, means including a second discharge tube cooperating with said condenser to time a period of right of way in said second lane appreciably longer than said minimum in said second lane, and means responsive to operation of said second discharge tube upon such transfer to cause retransfer to said second lane sooner than retransfer is caused responsive to operation only of the first discharge tube upon such transfer.

11. In a tralc signal control system for an intersection of traic lanes having vehicle responsive devices in the lanes, a right of way controller to transfer right of Way to one lane from a Second lane in response to actuation of the vehicle responsive device in the first lane and thereafter to permit right of way to be retransferred to the second lane in response to actuation of the vehicle responsive device therein, a condenser and a charging circuit connected thereto, means including a discharge tube cooperating with said condenser to time a minimum period of right of way in said second lane before transfer to said rst lane in response to actuation of said device, means including a second discharge tube cooperating with said condenser to time a period of right of Way in said second lane appreciably longer than said minimum in said second lane, and means responsive to operation of said second discharge tube upon such transfer to permit right of Way to be retransferred to the said second lane in response to actuation therein, sooner than retransfer Ais permitted responsive to operation only of the rst discharge tube upon such transfer.

12. A traic control vsystem for interfering traffic lanes having traic actuatable means in each of the lanes and a right of Way controller c connected to said tranic actuatable means for governing accord of right of way to the lanes, said controller including a cyclic switch having two parts to its cycle and adapted when in one part to cause accord of right of way to only one of the lanes and when in the other to cause accord of right of Way only to the other lane, and each part of said switch cycle consisting of a rst or initial interval and a latter or vehicle interval, timing means including a condenser, means including a resistance for charging said condenser, means responsive to a predetermined charge on said condenser to advance said switch from the initial to the vehicle interval of Vone part of its cycle and in response to an actuation of the traiiic actuatable means on said other lane occurring prior to said condenser reaching said predetermined charge to advance said switch from said one part of the cycle to the other part, means responsive to actuation of the traio actuatableV means in said one lane when said switch is in the vehicle interval of said one part of its cycle to reset the condenser for prolonging the time required to reach such predetermined charge, means including a relay and operating in the Vehicle interval of said one part of the switch cycle responsive to a higher predetermined charge on said condenser for operating said relay upon actuation of said other lane after said charge 1s reached, means for maintaining said relay energized until and during said initial interval of said other part of the switch cycle, and contact means on said relay operating in the initial interval of said other part of the switch cycle to shunt the resistance over which the condenser is normally charged to cause substantially immediate advance of the switch to the vehicle interval of said other part of the switch cycle.

ALFRED PERCY BAILEYRENSHAW. 

